Drying an extreme ultraviolet (EUV) pellicle

ABSTRACT

Systems and methods for rinsing one or more pellicles during fabrication, including immersing and soaking the one or more pellicles in a rinse bath solution for a particular time period, forming a top layer above the rinse bath solution, the top layer having a lower surface tension than the rinse bath, and withdrawing the one or more pellicles through the top layer for drying.

BACKGROUND Technical Field

The present invention relates to Extreme Ultraviolet (EUV) pelliclefabrication, and more particularly to drying EUV pellicles during EUVpellicle fabrication.

Description of the Related Art

During semiconductor wafer fabrication, extreme ultraviolet (EUV) lightmay be employed in, for example, a lithographic process to enabletransfer of very small patterns (e.g., nanometer-scale patterns) from amask to a semiconductor wafer. In EUV lithography, a pattern formed onan EUV lithographic mask (e.g., EUV reticle) may be transferred to asemiconductor wafer by reflecting EUV light off of portions of areflective surface. A pellicle can be placed in front of the mask to,for example, avoid contamination of the mask and to prevent unwantedparticles from reaching the mask surface, which may enable avoidance ofalteration of the pattern to be transferred by the mask.

In the case of EUV mask technology, pellicles are conventionally verythin (e.g., ˜100 nm or less), therefore managing the mechanicalstability of the ultra-thin pellicle membrane in the presence of outsideforces (e.g., capillary force, vibrations, etc.) during fabrication ischallenging, especially given the large surface area with respect to thethickness of an EUV pellicle. Among the plurality of forces which may beexerted on an EUV pellicle surface, a comparatively difficult force toovercome is the presence of a capillary force during the withdrawal ofthe membrane from a rinse bath (e.g., de-ionized water (DI H₂O)) fordrying of the pellicle. Such capillary force is operative at theliquid-gas-solid boundary on both sides of the partially immersedmembrane, and may result in a downward pulling force, which may bedescribed by the Wilhelmy equation (e.g., F=2·γ·l cos θ). Such force (F)may break even small EUV pellicles while the pellicle is being withdrawnfrom the rinse bath.

Conventional systems and methods that minimize the surface tension (γ)of the drying liquid may force a fluid flow (e.g., Marangoni drying,critical point drying, etc.), and may involve volumetric changes (e.g.,freeze drying), or specialty non-volatile chemicals (e.g., rinsesincluding surfactants, Langmuir Blodgett films, etc.). However, noconventional systems or methods can effectively and/or consistentlyfabricate ultra-thin, large-area EUV pellicles.

SUMMARY

A method for rinsing one or more pellicles during fabrication includesimmersing and soaking the one or more pellicles in a rinse bath solutionfor a particular time period. A top layer is formed above the rinse bathsolution, the top layer having a lower surface tension than the rinsebath, and the one or more pellicles are withdrawn through the top layerfor drying.

A system for rinsing one or more pellicles during fabrication includes acontainer, and a rinse bath solution, disposed in the container, forimmersing and soaking the one or more pellicles for a particular timeperiod. A top layer is formed above the rinse bath solution afterimmersing the one or more pellicles in the rinse bath solution. The toplayer has a lower surface tension than the rinse bath, and a withdrawalmechanism withdraws the one or more pellicles from the container afterimmersion.

A method for rinsing one or more pellicles during fabrication includesimmersing and soaking the one or more pellicles in a rinse bath solutionfor a particular time period. A top layer is formed above the rinse bathsolution, the top layer being less dense, and having a lower surfacetension than the rinse bath, and the one or more pellicles are withdrawnthrough the top layer for drying.

These and other features and advantages will become apparent from thefollowing detailed description of illustrative embodiments thereof,which is to be read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure will provide details in the following description ofpreferred embodiments with reference to the following figures wherein:

FIG. 1 shows an exemplary system employing a pellicle (e.g., extremeultraviolet (EUV) pellicle) for lithography, in accordance with oneillustrative embodiment of the present principles;

FIG. 2 shows an exemplary system for pellicle (e.g., EUV pellicle)fabrication, in accordance with one illustrative embodiment of thepresent principles;

FIG. 3 shows an exemplary system/method for rinsing and/or drying apellicle (e.g., EUV pellicle) during pellicle fabrication, in accordancewith one illustrative embodiment of the present principles; and

FIG. 4 is a block/flow diagram illustratively depicting a method forrinsing and/or drying a pellicle (e.g., EUV pellicle) during pelliclefabrication, in accordance with one illustrative embodiment of thepresent principles.

DETAILED DESCRIPTION

The present principles are directed to systems and methods for dryingone or more Extreme Ultraviolet (EUV) pellicles during EUV fabrication.

Advanced patterning techniques (e.g., KrF (248 nm), ArF (193 nm, etc.))for lithography may employ projection-reduction imaging systems thatmake use of a photomask (e.g., including the physical image to transferthe desired layout to a semiconductor substrate (e.g., wafer)). Toenable a faithful image transfer, physical images/patterns present onthe photomask should be free of defects or particulates to avoid theimage printing of such foreign material (FM) onto the photoresist layerduring lithographic exposure.

As such, the semiconductor industry has adopted the use of protectivepellicles for a plurality of lithographic wavelengths, and a protectivepellicle may be fabricated according to various embodiments of thepresent principles (described in further detail herein below). Apellicle may include a thin (e.g., ˜1 micron) polymeric film (e.g.,nitrocellulose, Polytetrafluoroethylene (PTFE) (e.g., forms of Teflon™,etc.), and may be mounted on a supporting frame which is glued to thephotomask, resting at a short distance (e.g., ˜6 mm) away from the masksurface. At this distance, any foreign material (FM) that lands on thepellicle surface will be located far enough away from the focal planeduring the image transfer process so that it will not create a foreignpattern on the photoresist layer. The area of a commercial pellicle isconventionally commensurate to the size of a production photomask (e.g.,6×6 inches), and needs to be highly transparent to the imagingwavelength, relatively tensile to avoid wrinkling or sagging, andresistant to radiation damage. The pellicle has become an integralcomponent in the manufacturing process for most Integrated Circuit (IC)manufacturers and high-resolution projection photolithography systemsused in, for example, the manufacturing of thin film magnetic readingheads, liquid crystal display (LCD) flat panels, micro electromechanicalsystem (e.g., MEMS), etc.

In one embodiment, pellicles, as fabricated using the presentprinciples, may also be employed during EUV lithography (e.g.,wavelength equal to 13.5 nm), which is a prospective lithographictechnique (e.g., for 7 nm semiconductor technology node and beyond).However, a pellicle material that is suitable for EUV applications mayuse of extremely thin layers due to the strong absorption of EUVradiation by dense matter. For example, an EUV pellicle based on siliconor silicon nitride may achieve 90% transparency for the single pass ofan EUV ray of light by employing a thicknesses of 50 nm or 15 nm,respectively.

Several EUV pellicle materials have been employed or proposed,including, for example, polycrystalline silicon, monocrystallinesilicon, graphitic carbon, carbon nanotubes, etc.

In one embodiment, fabrication of a pellicle suitable for EUV imagingmay be performed by selectively etching a wafer (e.g., silicon)including a pellicle material layer to create a desired free standingmembrane (e.g., pellicle). This subtractive method may employ wetprocessing methods and chemicals, so that the ultra-thin unsupportedfilm (e.g., pellicle) is able to withstand forces exerted on its surfaceduring etching and rinsing without breaking. Examples of forces that maybe exerted on a pellicle during etching and/or rinsing includemechanical vibrations induced during manual pellicle handling or bymoving parts that assist with controlled motorized translation, liquidor air pressure differentials on either side of the membrane (e.g.,pellicle) because of forced or natural convection and capillary forcesfrom meniscus formation at the liquid-air interface, etc.

Conventional systems and methods which minimize the capillary force ofthe drying liquid are, for example, the Marangoni drying (whichincorporates the use of a flow of organic vapor) for drying a photomask,and the use of a flow of organic liquid for drying of a photomask.However the application of either one of such methods to the drying ofan EUV pellicle is unsuitable due to the forced fluid flow, which maydamage the EUV pellicle. Managing the mechanical stability of theultra-thin membrane (e.g., pellicle) in the presence of such forces isparticularly challenging given the comparatively large area of the EUVpellicle to its thickness.

In one embodiment, the present principles may form a layer (e.g.,supernatant polar organic layer) on top of a rinse bath (e.g.,de-ionized water (DI H₂O) rinse bath), and the layer may be stagnantduring withdrawal of the EUV pellicle from the rinse bath. The presentprinciples enable removal from of the wetted membrane (e.g., wetted EUVpellicle) from the rinse bath in the presence of a low-surface-tensionfluid (e.g., lower surface tension/capillary force than the rinse bath)that is miscible with water without causing any deleterious effects onthe EUV pellicle that result from such withdrawal using conventionalsystems and methods.

In a particularly useful embodiment, the supernatant polar organic layermay be formed by introducing a floating alcohol layer on top of a rinsebath (e.g., DI H₂O rinse bath) after a membrane (e.g., EUV pellicle) hasbeen removed from, for example, a wet etch tank and immersed fully intothe rinse bath. The membrane (e.g., EUV pellicle) may be soaked in therinse bath bottom layer to dilute and/or eliminate any residualchemicals (e.g., etching chemicals) from the membrane. The membrane maythen be withdrawn from the rinse bath bottom layer by traversing throughthe top floating alcohol layer before being dried in, for example, anatmospheric environment of a manufacturing facility, and the floatingalcohol layer may leave no residue on the pellicle after withdrawal fromthe rinse bath.

In various embodiments, suitable alcohols for use as the floatingalcohol layer may include, for example, alcohols with lower density thanwater, relatively low surface tension (e.g., lower than water), goodwater solubility, and/or high viscosity. Some examples of suitablealcohols include iso-propanol (e.g., density=0.786 g/cm³, surfacetension (γ)=21.32 mN/m at 20° C.; water solubility=fully miscible;viscosity=1.96 cP at 25° C.), and n-propanol (e.g., density=0.803 g/cm³;γ=23.8 mN/m at 20° C.; water solubility=fully miscible; viscosity=1.96cP at 25° C.).

It is to be understood that the present invention will be described interms of a given illustrative architecture; however, otherarchitectures, structures, substrate materials and process features andsteps may be varied within the scope of the present invention.

It will also be understood that when an element such as a layer, regionor substrate is referred to as being “on” or “over” another element, itcan be directly on the other element or intervening elements may also bepresent. In contrast, when an element is referred to as being “directlyon” or “directly over” another element, there are no interveningelements present. It will also be understood that when an element isreferred to as being “connected” or “coupled” to another element, it canbe directly connected or coupled to the other element or interveningelements may be present. In contrast, when an element is referred to asbeing “directly connected” or “directly coupled” to another element,there are no intervening elements present.

The present embodiments may include a design for an integrated circuitchip and/or EUV pellicle, which may be created in a graphical computerprogramming language, and stored in a computer storage medium (such as adisk, tape, physical hard drive, or virtual hard drive such as in astorage access network). If the designer does not fabricate chips or thephotolithographic masks used to fabricate chips, the designer maytransmit the resulting design by physical means (e.g., by providing acopy of the storage medium storing the design) or electronically (e.g.,through the Internet) to such entities, directly or indirectly. Thestored design is then converted into the appropriate format (e.g.,GDSII) for the fabrication of photolithographic masks, which typicallyinclude multiple copies of the chip design in question that are to beformed on a wafer. The photolithographic masks are utilized to defineareas of the wafer (and/or the layers thereon) to be etched or otherwiseprocessed.

Methods as described herein may be used in the fabrication of integratedcircuit chips. The resulting integrated circuit chips can be distributedby the fabricator in raw wafer form (that is, as a single wafer that hasmultiple unpackaged chips), as a bare die, or in a packaged form. In thelatter case the chip is mounted in a single chip package (such as aplastic carrier, with leads that are affixed to a motherboard or otherhigher level carrier) or in a multichip package (such as a ceramiccarrier that has either or both surface interconnections or buriedinterconnections). In any case the chip is then integrated with otherchips, discrete circuit elements, and/or other signal processing devicesas part of either (a) an intermediate product, such as a motherboard, or(b) an end product. The end product can be any product that includesintegrated circuit chips, ranging from toys and other low-endapplications to advanced computer products having a display, a keyboardor other input device, and a central processor.

It should also be understood that material compounds will be describedin terms of listed elements (e.g., SiN). These compounds includedifferent proportions of the elements within the compound (e.g., SiNincludes Si_(x)N_(1-x) where x is less than or equal to 1, etc. Inaddition, other elements may be included in the compound, and stillfunction in accordance with the present principles. The compounds withadditional elements will be referred to herein as alloys.

Reference in the specification to “one embodiment” or “an embodiment” ofthe present principles, as well as other variations thereof, means thata particular feature, structure, characteristic, and so forth describedin connection with the embodiment is included in at least one embodimentof the present principles. Thus, the appearances of the phrase “in oneembodiment” or “in an embodiment”, as well any other variations,appearing in various places throughout the specification are notnecessarily all referring to the same embodiment.

It is to be appreciated that the use of any of the following “/”,“and/or”, and “at least one of”, for example, in the cases of “A/B”, “Aand/or B” and “at least one of A and B”, is intended to encompass theselection of the first listed option (A) only, or the selection of thesecond listed option (B) only, or the selection of both options (A andB). As a further example, in the cases of “A, B, and/or C” and “at leastone of A, B, and C”, such phrasing is intended to encompass theselection of the first listed option (A) only, or the selection of thesecond listed option (B) only, or the selection of the third listedoption (C) only, or the selection of the first and the second listedoptions (A and B) only, or the selection of the first and third listedoptions (A and C) only, or the selection of the second and third listedoptions (B and C) only, or the selection of all three options (A and Band C). This may be extended, as readily apparent by one of ordinaryskill in this and related arts, for as many items listed.

Referring now to the drawings in which like numerals represent the sameor similar elements and initially to FIG. 1, an exemplary system 100employing a pellicle 108 (e.g., extreme ultraviolet (EUV) pellicle) isillustratively depicted in accordance with an embodiment of the presentprinciples. In an embodiment, one or more EUV pellicles 108 may beattached to a frame 104, and may act as a barrier to keep particles 109(e.g., contamination) away from an imaging (e.g., focal) plane 106 whileallowing EUV light 110 to pass through when performing imaging of, forexample, an EUV mask 102. In an embodiment, an EUV pellicle 108 mayinclude a large area-to-thickness unsupported membrane that is extremelyfragile and sensitive to stress (e.g., in terms of force applied to aparticular cross-sectional area of the pellicle 108.

In one embodiment, an EUV pellicle 108 may be fabricated from aplurality of materials according to various embodiments of the presentprinciples. For example, an EUV pellicle 108 may be fabricated fromultra-thin polysilicon (e.g., 50 nm thick) or silicon nitride (e.g., 15nm thick), although other materials may be employed according to variousembodiments of the present principles.

Referring now to FIG. 2, an exemplary system 200 for pellicle (e.g., EUVpellicle) fabrication is illustratively depicted in accordance with anembodiment of the present principles. In one embodiment, one or more EUVpellicles 208 may be fabricated using, for example, a subtractive (e.g.,wet etch) process, and the pellicles 208 may be rinsed in a rinse bathcontainer 202 to remove any residue (e.g., chemical residue) left on thepellicle 208 from, for example, wet etching.

In an embodiment, the rinse bath container 202 may include a rinse bathsolution 204 (e.g., DI H₂O), and a layer 206 (e.g., supernatant polarorganic layer) with relatively low surface tension (e.g., as compared toDI H₂O) for controlling capillary forces during withdrawal of thepellicle 208 from the rinse bath solution 204 (e.g., DI H₂O). In anembodiment, the supernatant polar organic layer 206 may be introduced tothe rinse bath container 202 after immersing the pellicle 208 in therinse bath solution according to the present principles, and will bedescribed in further detail herein below. In an embodiment, a pelliclewithdrawal device 201 may be employed for withdrawing the pellicle fromthe rinse bath 204. In one embodiment, the layer 206 may include two ormore layers (e.g., of different materials), and the two or more layersmay include materials with different densities, capillary forces, etc.according to the present principles.

Referring now to FIG. 3, an exemplary system/method 300 for rinsingand/or drying a pellicle (e.g., EUV pellicle) during fabrication isillustratively depicted in accordance with an embodiment of the presentprinciples. In one embodiment, a rinse bath solution 304 (e.g., DI H₂O)may be introduced into a container 302 (e.g., rinse bath container). Apellicle 308 (e.g., EUV pellicle) may be immersed and soaked in therinse bath solution 304 to remove any residual etching chemicals (e.g.,KOH). The EUV pellicle 308 may be soaked for a pre-determined period oftime in the rinse bath 304 at phase 301, and a supernatant polar organic(e.g., alcohol) layer 306 may be formed on top of the rinse bathsolution 304 at phase 303 according to the present principles. In anembodiment, the alcohol layer 306 may be formed after the pellicle 308has been fully immersed in the rinse bath 304. In other embodiments, analcohol layer 306 may be floated on top of the rinse bath solution 304before immersion of the EUV pellicle 308 according to the presentprinciples.

In an embodiment, after soaking the pellicle 308 in the rinse bath 304to remove residual etching chemicals at phase 301, the pellicle 308 maybe withdrawn from the rinse bath 304 through the alcohol layer 306 atphase 305 and dried at phase 307 in, for example, the atmosphericenvironment of a manufacturing facility. In an embodiment, removing thepellicle 308 through an alcohol layer 306 prevents breaking of thepellicle 308 because the top alcohol layer 306 has lower capillaryforces present at the liquid-air junction than the rinse bath 304.

In an embodiment, the alcohol layer 306 may be a stagnant layer, and thesurface tension of the alcohol layer 304 may be less than that of water(e.g., 20 mN/m) according to the present principles. In someembodiments, the top stagnant layer may include a surface tensionbetween 20 mN/m and 30 mN/m. In some embodiments, alcohols for use asthe supernatant polar organic layer 306 may include alcohols withdensity lower than water, low surface tension (in comparison to water),good water solubility, and/or high viscosity (in comparison to water)according to the present principles. Examples of alcohols for use as thealcohol layer 306 and their properties in comparison to properties ofwater are illustratively depicted in the following table:

TABLE 1 SURFACE H₂O FLUID DENSITY TENSION SOLUBILITY VISCOSITY Water(H₂O) 1.0 g/cm³ 72 mN/m N/A 1.0 cP Isopropanol 0.786 g/cm³ 21.32 mN/mCompletely 1.96 cP (IPA) Miscible n-propanol 0.803 g/cm³ 23.8 mN/mCompletely 1.96 cP Miscible

In an embodiment, although the fluids (e.g., iso-propyl alcohol (IPA),n-propanol, etc.) employed as the alcohol layer 306 are fully misciblein water, they form phases that remain distinctly separated from waterfor several hours, which is enough time for rinsing and withdrawing ofthe pellicle according to the present principles. Although the aboveliquids are listed as candidates for the supernatant polar organic layer306 (e.g., alcohol layer), any liquids with similar properties (e.g.,density lower than water, surface tension lower than water, etc.) may beemployed as the top layer 306 according to various embodiments of thepresent principles.

Referring now to FIG. 4, a method 400 for rinsing and/or drying apellicle (e.g., EUV pellicle) during fabrication is illustrativelydepicted in accordance with an embodiment of the present principles. Inone embodiment, a rinse bath may be formed in block 402, and the rinsebath may comprise, for example, de-ionized water (DI H₂O) according tothe present principles. In block 404, a pellicle (e.g., EUV pellicle)may be immersed in the rinse bath, and the pellicle may be soaked in therinse bath for a particular period of time (e.g., seconds, minutes,hours, etc.) to remove any residual etching chemicals (e.g., KOH) fromthe pellicle. The particular period of time may vary depending on aplurality of factors (e.g., concentration and type of dissolved solidsin the wet etchant, viscosity and density of the residual etching layerattached to the pellicle surface, etc.).

In block 408, a supernatant polar organic layer (e.g., alcohol) may beformed on top (e.g., floated) of the rinse bath (e.g., DI H₂O) after thepellicle has been immersed and soaked in the rinse bath in blocks 404and 406, respectively, according to an embodiment of the presentprinciples. As described above with reference to FIG. 3, alcohols foruse for formation of the supernatant polar organic layer may includealcohols with densities lower than water, low surface tension (incomparison to water), complete miscibility with water, and/or highviscosity (in comparison to water) according to various embodiments ofthe present principles.

In block 408, during formation of the supernatant polar organic layer(e.g., alcohol layer), although the fluids (e.g., IPA, n-propanol, etc.)employed as the alcohol layer may be fully miscible in water, they formphases that may remain distinctly separated from water for severalhours, which is enough time for rinsing and withdrawing of the pellicleaccording to the present principles. Although the above liquids arelisted as candidates for the supernatant polar organic layer (e.g.,alcohol layer), any liquids with similar properties (e.g., density lowerthan water, surface tension lower than water, etc.) may be employed forformation of the alcohol layer in block 408 according to variousembodiments of the present principles.

In block 410, the pellicle (e.g., EUV pellicle) may be withdrawn fromthe rinse bath through the layer (e.g., alcohol layer) formed in block408, and may be dried in block 412 in, for example, an atmosphericenvironment of a manufacturing facility. Withdrawing the pelliclethrough an alcohol layer may prevent breaking of the pellicle becausethe top alcohol layer formed in block 408 may exert lower capillaryforces at the liquid-air junction than the rinse bath solution alone. Inan embodiment, the alcohol layer formed in block 408 may be a stagnantlayer, and the surface tension of the alcohol layer may be less thanthat of water (e.g., 20 mN/m) according to the present principles. Insome embodiments, alcohol is used for the layer in block 408 as alcoholmay evaporate from the pellicle without leaving any residue.

Having described preferred embodiments of a system and method (which areintended to be illustrative and not limiting), it is noted thatmodifications and variations can be made by persons skilled in the artin light of the above teachings. It is therefore to be understood thatchanges may be made in the particular embodiments disclosed which arewithin the scope of the invention as outlined by the appended claims.Having thus described aspects of the invention, with the details andparticularity required by the patent laws, what is claimed and desiredprotected by Letters Patent is set forth in the appended claims.

What is claimed is:
 1. A method for rinsing one or more pellicles,comprising: forming a stagnant top layer above a rinse bath, thestagnant top layer comprising a stagnant alcohol layer having a lowersurface tension than the rinse bath; immersing and soaking the one ormore pellicles in the rinse bath including the stagnant top layer for aparticular time period; and withdrawing the one or more pelliclesthrough the stagnant top layer for drying.
 2. The method of claim 1,wherein the one or more pellicles includes one or more extremeultraviolet (EUV) pellicles.
 3. The method of claim 1, wherein the rinsebath comprises deionized water (DI H₂O).
 4. The method of claim 1,wherein the top layer comprises a supernatant polar organic layer. 5.The method of claim 1, wherein the top layer comprises a stagnantalcohol layer with a surface tension between 20 mN/m and 30 mN/m.
 6. Themethod of claim 1, wherein the top layer is formed from completelymiscible materials, wherein the completely miscible materials of the toplayer remain distinctly separated from the rinse bath for two or morehours.
 7. The method of claim 1, wherein the one or more pellicles areformed by a subtractive process, the subtractive process including wetetching.
 8. The method of claim 1, wherein the one or more pellicles areformed from one of polycrystalline silicon, monocrystalline silicon, orsilicon nitride.
 9. The method of claim 1, wherein the one or morepellicles are formed from one of graphitic carbon or carbon nanotubes.10. A method for rinsing one or more membranes, comprising: forming astagnant top layer above a rinse bath solution, the stagnant top layercomprising a stagnant alcohol layer having a lower surface tension thanthe rinse bath solution; immersing and soaking the one or more membranesin the rinse bath solution including the stagnant top layer for aparticular time period; and withdrawing the one or more membranesthrough the stagnant top layer for drying.
 11. The method of claim 10,wherein the one or more membranes comprises one or more extremeultraviolet (EUV) pellicles.
 12. The method of claim 10, wherein therinse bath solution comprises deionized water (DI H₂O).
 13. The methodof claim 10, wherein the top layer comprises a supernatant polar organiclayer.
 14. The method of claim 10, wherein the top layer comprises astagnant alcohol layer with a surface tension between 20 mN/m and 30mN/m.
 15. The method of claim 10, wherein the top layer is formed fromcompletely miscible materials, wherein the completely miscible materialsof the top layer remain distinctly separated from the rinse bathsolution for two or more hours.
 16. The method of claim 10, wherein theone or more membranes are formed by a subtractive process, thesubtractive process including wet etching.
 17. The method of claim 10,wherein the one or more membranes are formed from one of polycrystallinesilicon, monocrystalline silicon, or silicon nitride.
 18. The method ofclaim 10, wherein the one or more membranes are formed from one ofgraphitic carbon or carbon nanotubes.
 19. A method for rinsing one ormore membranes during fabrication, comprising: forming a stagnant toplayer above a rinse bath solution, the stagnant top layer comprising astagnant alcohol layer having a lower surface tension than the rinsebath solution; immersing and soaking the one or more membranes in therinse bath solution including the stagnant top layer for a particulartime period; and withdrawing the one or more membranes through thestagnant top layer for drying.
 20. The method of claim 19, wherein thetop layer is formed from completely miscible materials, wherein thecompletely miscible materials of the top layer remain distinctlyseparated from the rinse bath solution for two or more hours.